Chemical Analysis

• Lithium produces a crimson flame test
• Sodium produces a yellow flame
• Potassium produces a lilac flame
• Calcium produces an orange-red flame
• Copper produces a green flame
• You can add sodium hydroxide solutions of calcium, magnesium and alumnium ions
• Calcium ions, magnesium ions and aluminum ions all produce white precipitates

  If we add excess sodium hydroxide solution to aluminum then we get a colourless solution.

  Need to use flame tests to distinguish between magnesium and calcium.
• Ca(NO3)2 + 2NaOH → 2NaNO3 + Ca(OH)2

  Calcium Nitrate+ Sodium Hydroxide → Sodium Nitrate + Calcium Hydroxide
• Mg(NO3)2 + 2NaOH → 2NaNO3 + Mg(OH)2 Magnesium Nitrate+ Sodium Hydroxide → Sodium Nitrate + Magnesium Hydroxide
• Al(NO3)3 + 3NaOH →2NaNO3 + Al(OH)3

  Aluminum Nitrate+ Sodium Hydroxide → Sodium Nitrate + Aluminum Hydroxide
• Adding sodium hydroxide to other metal ions producing other colours of precipitates
• Copper(II) Nitrate + Sodium Hydroxide → Sodium Nitrate + Copper(II) Hydroxide

  Cu(NO3)2 + 2NaOH → 2NaNO3+Cu(OH) 2

  Blue precipitate
• Iron(II) Nitrate + Sodium Hydroxide → Sodium Nitrate + Iron(II) Hydroxide Fe(NO3)2 + 2NaOH → 2NaNO3+Fe(OH) 2. Green precipitate
• Iron(III) Nitrate + Sodium Hydroxide → Sodium Nitrate + Iron(III) Hydroxide Fe(NO3)3 + 3NaOH → 2NaNO3+Fe(OH) 3

  Brown Precipitate
• Identify Carbonate

  Add dilute acid to sample.

  Acid will react with carbonate to produce carbon dioxide gas. effervescence.

  Bubble gas through limewater, goes cloudy if carbon dioxide.
• Testing for Halide Ions

  Add nitric acid to the sample.

  Add dilute silver nitrate solution.

  Halide ions produce a precipitate of the silver Halide.

  Chlorine- White precipitate of Silver chloride

  Bromide- Cream Precipitate of Silver Bromide

  Iodine- Yellow precipitate of silver iodide
• Testing for sulfate ions

  Add HCL to sample

  Add barium chloride

  A white precipitate if sulfate ions re present